Semiconducting ceramic compositions based on polycrystalline strontium titanate having internal insulated grain boundaries are known for use as capacitor dielectric materials. Such ceramic materials, examples of which are described in U.S. Pat. Nos. 3,933,668 and 4,143,207, can have high dielectric constants and desirable temperature and voltage characteristics. In the past, these ceramic materials have typically been made by a process requiring two high-temperature firing steps, viz., a first step to produce a densified semiconducting ceramic composition and a second step to insulate the grain boundaries. While the semiconducting compositions based on strontium titanate heretofore known can have many desirable properties, they also have relatively large grain sizes, generally above 25 microns and typically greater than 50 microns, regardless of the particle size of the titanate powder used in their preparation. Accordingly, while such ceramic compositions are suitable for use as dielectrics in many forms of capacitors, they cannot be used in thin-layer, multilayer capacitors, particularly those in which the dielectric layer desirably has a thickness less than 20 microns.